1. Field of the Invention
The invention relates to a hub body for clutches, especially friction clutches in motor vehicles. More particularly to hub body having internal toothing for connection to a gear input shaft and with at least one encircling shoulder extending radially outward or with elements spaced in the circumferential direction and extending radially and axially for connection to a take-along disk of the clutch.
2. Description of the Related Art
Hub bodies of this type are used for friction clutches that have a pre-damper. German reference DE 40 26 765 A1 discloses a clutch disk with an idle system and a load system. The internal toothing of the hub or hub body, which is equipped with external toothing for transmission of torque, is placed on the gear input shaft. A center disk (take-along disk) is connected to the hub body by the external toothing, whereby the external toothing has a rotational clearance that determines the effective area of the idle system. All components of the torsional vibration damper are arranged concentrically around the rotational axle. The center disk is connected to a lining carrier, which carries the friction linings on its external circumference, via which the torque is initiated. The torque is fed to the hub body via the external toothing, and from there to the gear input shaft via the internal toothing.
The hub body, as the final member of the power flow chain, is subjected to high loads. The teeth, as the elements transmitting torque, are known to be exposed to high surface pressure. To achieve sufficient strength and operational reliability, the hub body must be made from suitably high-tempered steel. The largest component load can be expected in the toothing. It follows that when materials are chosen, steels with strength values above the load expected in the toothing are desirable. Such materials are correspondingly expensive.
To reduce the costs when selecting materials, the hub bodies are usually hardened after forging. As a result, strength increases uniformly around the circumference of the hub body. This means, for example, that the toothing has almost the same strength to a certain radial depth at every point. Hardening a part requires a further work step, so that manufacturing costs of the hub body are high.